The Recurring Question: Where Do Fast Radio Bursts Come from? - Scientific American - For more than a decade, researchers have sought to solve the puzzle of fast radio bursts, millisecond chirps of radio waves that seem to appear at random in the sky, likely from unknown sources millions or even billions of light-years away. Theorists have many ideas for what causes them, including stellar flares, cataclysmic mergers of neutron stars and evaporating black holes. From X Isle